This invention relates generally to electrical testing instruments. Heretofore electrical testing instruments have been generally made with a pair of probes on the ends of two extension cords which must each be separately held in every use of the instrument, so that both hands are occupied therewith. Very often a test requires applying the two probes against electrical contacts which are a standard fixed distance apart, such as the contacts inside a wall electric outlet socket. It seems impractical that both hands must be employed for such applications, whereas one hand alone could do it if the probes were a fixed distance apart, so as to free the other hand for other use.